he's part of a major new study at the baltimore v.a. and the university of maryland. >> your heart rate was wonderful. >> narrator: and oddly enough, dr. lisa shulman says it's one of the first times the impact of exercise on parkinson's has been evaluated. >> maybe there's been a cultural perspective that has embraced pharmaceutical and surgical approaches, and has considered lifestyle changes to be very soft and not as worthy of study. any pain in your legs or your arms or anything? >> no. >> okay, great job. but it's not at all hard for me to imagine that the results of a properly designed exercise program are going to be more effective than many of the medications we have now. >> here we go, we're starting you up. >> that's all right, i'm starting you off. >> narrator: if time on the treadmill is as important as the pills you take, it may be because exercise increases something called growth factors, proteins that scientists think are essential to support the brain. >> when your dopamine neurons grow very early on in development they require growth factors for nurturing. if that neu